[NET]: Introduce protocol-specific destructor for time-wait sockets.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_timewait_sock.h

@@ -196,6 +196,7 @@ static inline void inet_twsk_put(struct inet_timewait_sock *tw)
 {
 	if (atomic_dec_and_test(&tw->tw_refcnt)) {
 		struct module *owner = tw->tw_prot->owner;
+		twsk_destructor((struct sock *)tw);
 #ifdef SOCK_REFCNT_DEBUG
 		printk(KERN_DEBUG "%s timewait_sock %p released\n",
 		       tw->tw_prot->name, tw);

include/net/timewait_sock.h

@@ -19,6 +19,7 @@ struct timewait_sock_ops {
 	unsigned int	twsk_obj_size;
 	int		(*twsk_unique)(struct sock *sk,
 				       struct sock *sktw, void *twp);
+	void		(*twsk_destructor)(struct sock *sk);
 };
 
 static inline int twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
@@ -28,4 +29,10 @@ static inline int twsk_unique(struct sock *sk, struct sock *sktw, void *twp)
 	return 0;
 }
 
+static inline void twsk_destructor(struct sock *sk)
+{
+	if (sk->sk_prot->twsk_prot->twsk_destructor != NULL)
+		sk->sk_prot->twsk_prot->twsk_destructor(sk);
+}
+
 #endif /* _TIMEWAIT_SOCK_H */